1. Field of the Invention
This invention generally relates to a spray coating system with constant pressure, and more particularly, to a spray coating system with constant pressure which uses the magnetic induction effect to perform the stirring function.
2. Description of the Prior Art
The traditional packaging process of light emitter diode (LED) mainly comprises: chip inspection, wafer expending, dispensing (backing adhesive operation), manual wafer probing or automatic mounting bracket, sintering, bonding, packaging, curing, cutting and testing, etc. Specifically, in the process of dispensing, the paste dispenser is used to drip the adhesive on corresponding locations of the LED brackets after mixing the epoxy resin with the phosphor or the silver powder according to the proper proportion. Next, the manual wafer probing or the automatic mounting bracket is performed. The traditional dispensing process has the advantages of low cost and big quantity, and its disadvantage is more difficult to control the dispensing rate. Because many detailed requirements about the phosphor distribution ratio, the adhesive height, the dispensing location and the likes need to be noticed, it will generate many problems if not follow these detailed requirements, for example, color from LED non-uniform, color temperature difference, or the color from LED looks too much yellow because adding too much the phosphor, or the color from LED looks too much blue because adding too less the phosphor.
Thereby, the dispensing process improved is applied to perform the spray coating operation. The spray coating operation is performed by the automatic spray coating device after mixing the sold formulation (the phosphor or silver powder) and mixture (the epoxy resin) to generate the mixture material according to the specified proportion. The advantage of the dispensing process improved is that the coating thickness can be easily controlled, and the execution speed is faster than the tradition dispensing process. However, the dispensing process improved easily leads to remain or accumulate the mixture material in the nozzle to block the nozzle or make the composition heterogeneity of the packaging material so as to affect the product quality and the spray coating process.
Moreover, there is a dispensing process using the motor's blades to stir and mix the sold formulation (the phosphor or silver powder) and mixture (the epoxy resin) to generate the mixture material according to the proper proportion, so as to perform the spray coating operation by the automatic spray coating device with the motor's blades. The advantage is that the dispensing process applying the motor's blade can not easily lead to remain or accumulate the mixture material in the nozzle to block the nozzle or make the composition heterogeneity of the packaging material, and therefore, the composition of packaging material will be uniform distribution, and not block the nozzle. However, the dispensing process with the motor's blade will easily bring the pollutant or the extraneous matter into the packaging material when operating the motor's blade, so as to pollute the packaging material and affect the spray coating quality.
For the reason that the conventional spray coating system could not avoid the extraneous matter entering to the packaging material, a need has arisen to propose a novel scheme that may adaptively avoid the extraneous entering to the packaging material for preventing to pollute the packaging material, block the nozzle, generate the composition heterogeneity of the packaging material so as to advance the spray coating quality and efficiency.